From Longman Dictionary of Contemporary English in action someone or something that is in action is doing the job or activity they are trained or designed to do photos of ski jumpers in action see/watch something/somebody in action I’d like to see the new computer system in action. → action Examples from the Corpus in action • It's a chance for students to see a court in action.

in action, performing or taking part in a characteristic act: The school baseball team is in action tonight.

in action 1. Engaged in some activity. I think it's important to for students to see different businesses in action, so they get a sense of how things work when they leave school. 2. Having resumed a previous activity, especially after illness or injury. I need to take today off to deal with this cold, but I should be back in action on Monday.